Various sensors are currently utilized in various fields, such as avionics for control, as well as in the field of vehicle health monitoring. Hydraulic and Fly-by-Wire aircraft require the constant monitoring of various parameters, such as, but not limited to, pressure, temperature, voltage, current, actuator position used for control, safety and maintenance monitoring.
Current photonic technologies can be applied to various airborne vehicle management and control systems resulting in a significant reduction in weight, volume and cost as well as an inherent immunity to electromagnetic interference. A passive fiber optic sensor bundle, utilizing a single optically differentiating receiver array and incorporating various devices, such as temperature, pressure, voltage, current and motor/actuator position sensors into a single wavelength division multiplex (WDM) multimode fiber reduces the number of fibers required for vehicle operations and health monitoring.
A prior art system is illustrated in FIG. 1. This system includes a multi-wavelength transmitter 12 transmitting a spectrum of wavelengths over a single optical fiber 14. A plurality of WDM drop taps 16, 18, 20, and 22 are provided along the length of a first portion of the optical fiber line 14. Each of these WDM drop taps is associated with a particular sensor 24, 26, 28 and 30. Each of these sensors would be used to monitor the condition of various parameters or control devices. Each of the WDM drop taps would be sensitive to a particular narrow wavelength range and would split this narrow wavelength from the multi-wavelength spectrum to be transmitted to its particular sensor over optical fiber lines 42, 44, 46 and 48. Each of the sensors would modulate the narrow wavelength optical signal indicative of the parameter or control device monitored. These signals would then be sent over optical fiber lines 50, 52, 54, 56 to their respective WDM add taps 32, 34, 36 and 38. These combined, modulated signals would then be transmitted over an optical fiber line 60 to a multi-spectrum receiver 40. At that point, the signals received by the receiver 40 would then be analyzed.
The system shown in FIG. 1 including a centralized receiver array can be incorporated into a central control unit computer interface providing enhanced electromagnetic interference protection and supporting a modular repair/replacement strategy, while reducing the weight and volume of the sensing system. Various methods associated with a wide range of measurement parameters have been developed that would result in absolute, non-incremental, calibrated read-out of the particular physical environment.
The various sensor structures are compact, tolerant of extreme environments, and provide the accuracy, repeatability and response times required for optical fiber based control systems.
It is important to note that the prior art system illustrated in FIG. 1 does not utilize a spectrometer to analyze the results garnered from the myriad number of sensors provided in the system. Additionally, the prior art system does not utilize a time division multiplexing system for collecting the aforementioned data. Furthermore, the prior art system does not utilize an array of optical fiber lines.